[AHW34-P13] Relation between water component and geological conditions in Izu Islands
Keywords:spring water, groundwater, basaltic volcano, rhyolitic volcano, Izu Islands
Chemical composition of rock samples at 83 locations on each islands were analyzed by using a X-ray fluorescent spectrometry.
As a result, the water samples in the basaltic volcanic area showed high Mg²+ value to compare with the seawater ratio.
Also, it was found that the Mg2+/Ca2+ ratio of the water samples in the basaltic volcanic area and the Mg2+/Ca2+ ratio of the rock composition are almost the same. However, cation of water samples collected near Fudeshima in Oshima had higher value of Mg2+ content, which seams to be related with weathering process of highly porphyritic rocks of Fudeshima volcano.
In addition ,comparing the seawater composition ratio of SO42-/Cl- with the water sample, it was found that the water some samples from Oshima and all samples of Miyakejima contained a large amount of SO42- originated from volcanic SO2.